In one method of manufacturing electrical terminals, the terminals are stamped and formed from metal strip and are attached to a carrier strip. This carrier strip is useful for strip feeding the terminals through successive manufacturing operations. One necessary manufacturing operation involves plating, i.e., electroplating the electrical contact surfaces of the strip fed terminals with a contact metal, usually noble metals or noble metal alloys. These metals are characterized by good electrical conductivity and little or no formation of oxides that reduce the conductivity. Therefore, these metals, when applied as plating, will enhance conductivity of the terminals. The high cost of these metals has necessitated precision deposition on the contact surfaces of the terminals, and not on surfaces of the terminals on which plating is unnecessary.
Apparatus for plating is called a plating cell and includes an electrical anode, an electrical cathode comprised of the strip fed terminals, and a plating solution, i.e., an electrolyte of metal ions. A strip feeding means feeds the strip to a strip guide. The strip guide guides the terminals through a plating zone while the terminals are being plated. The plating solution is fluidic and is placed in contact with the anode and the terminals. The apparatus operates by passing electrical current from the anode through the plating solution to the terminals. The metal ions deposit as metal plating on those terminal surfaces in contact with the plating solution.
There are disclosed in U.S. Pat. No. 4,384,926 and 4,427,498, owned by this assignee, plating apparati in which the interior surfaces of strip fed terminals can be plated by supplying plating fluid through nozzles and over anode extensions that are mounted for reciprocation into and out of the interiors of terminals, said anode extensions being mounted within said nozzles.
The present invention is directed to an improved apparatus of the general type disclosed in the above patents. In the apparatus as disclosed herein the anode extensions are mounted separately and apart from the nozzles, each anode extension being associated with a corresponding nozzle. The anode extensions, however, enter the interior of the terminal from a different direction than that of the plating fluid. This improved apparatus permits a greater amount of plating solution to be flowed over the anode than is possible when the anode is contained within the nozzle. Further, this apparatus reduces the chances that any particulate matter will block the flow of the plating solution through the nozzle. Separating the anode extension and plating solution pathways also eliminates the possibility of particles becoming trapped between the anode and nozzle.
Since in the improved apparatus the anode extensions and plating fluid enter the terminal from different directions, closer tolerances can be maintained between the end of the anode extension and interior of the terminal.
The apparatus as disclosed herein is particularly adapted for plating strip fed terminals. The apparatus can also be used to plate loose piece terminals when used in conjunction with the loose piece plating apparatus disclosed in U.S. pat. application Ser. No. 564,279, now U.S. Pat. No. 4,473,445, filed Dec. 22, 1983, and owned by this assignee.
The apparatus in accordance with the invention is characterized in that a mandrel is rotated continuously as a strip of electrical terminals is fed continuously to the mandrel partially wrapped against the mandrel, and fed from the mandrel. The mandrel has a plurality of nozzles located around the mandrel's axis of rotation. The anode has a plurality of anode extensions which are associated with and aligned with but separate from said nozzles. The anode extensions are movable into and out of the interiors of the terminals that are against the mandrel. A conduit is provided which carries plating solution under pressure through the nozzles and upon the anode extensions. The nozzles inject plating solution into the interiors of the terminals in which the anode extensions have been received. A source of electrical potential supplies electrical current which flows from the anode extensions through the plating solution to the cathode, thus plating the interior surfaces of the terminals. The anode extensions are withdrawn from the interiors of the terminals as the terminals move out of the plating zone.